Robots, Life the Universe and Everything

Fresnel Lens Helmet (2010)

I bought a plastic fresnel lens from a dollar store, playing with it I imagined that if mounted in a helmet it could be used for an interesting costume. The idea was to position the lens about 20 to 30 cm in front of the user face so the magnifying effect will really show and to place some lights (LEDs) inside the helmet illuminating the user face to provide a TV like effect. During the weekend of Halloween 2010 I built this prototype using plastic fresnel lens, scratch wood materials, a skiing helmet, a PICAXE micro-controller with 8 LEDs, a rechargeable battery and a voltage regulator. A simple program to cycle through various light patterns was written.

It took me about 10 hours to do the prototype and it performed very well. It is a helmet that creates a really cool effect, specially at dark places or at night. The only real issue I found is that for the person wearing it looking through the fresnel lens is very difficult, specially with the lights flashing directly in front. If I ever do a second generation prototype I will use a couple of mirrors to provide a periscope type sight for the user and although the helmet is lighter that it looks and feels very comfortable as it is well balanced I would build a future version with lighter materials.

WARNING: Always use the helmet during night or indoors, never during day time and outdoors and never look at the sun with the helmet on. The lens will magnify the suns rays and could cause severe burns or eye damage to the user.

Use scratch pieces of wood. Start by cutting a frame for the lens. Note: This lense is broken so it was held together with some tape.

Use wood and screws to hold the lens in place.Get a helmet of some sort and then build a wood box with enough clearance for the helmet leaving 20 to 30 cms of space between the lens and the helmet. Leave space behind the helmet for the electronics adnd the battery.I used a thiker and heavier board for the back of the box to increase balance.This is the PICAXE CHI-030 board used. It contains a PICAXE-18X micro-controller. It is wired to 8 10 mm LEDS (2 white, 2 red, 2 green and 2 blue). Alternatively a simple flash light mounted inside the helmet can be used instead to provide simple illumination.PICAXE CHI-030 board with PICAXE 18X micro-controller and darlington driver IC.

I used 3 anchor points for the Helmet. A wood rod to hold the back of the Helmet an one tie wrap at each side.

Wood box painted black.PICAXE board, NiCd rechargeable battery, 7805 voltage regulator and power switch.Mounted 4 LEDs in a wood piece on each side.Installed 4 LEDs on each side of the fresnel lens. LEDs are pointing towards the helmet. Aluminum foil is used on one side of the LEDs to reflect more light. Paper is used on the other side of the LEDs to prevent ligh to go out towards the lens.

Completed fresnel lens helmet.Tests with daylight.

WARNING: Always use the helmet during night or indoors, never during day time and outdoors and never look at the sun with the helmet on. The lens will magnify the suns rays and could cause severe burns in the user.